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Kickback chain interference revisited...

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  • speedub_nate
    I thought I read everything there is to be read on the topic, and **thought** I had a magic gear combo figures out, but... I ve got the chain on my Xtracycle
    Message 1 of 23 , Feb 7, 2010
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      I thought I read everything there is to be read on the topic, and **thought** I had a "magic gear combo" figures out, but...

      I've got the chain on my Xtracycle conversion threaded neatly under the Freeradical , above the Kickback kickstand, and life looks good.

      Good, however, turns to ugly when I extend the Kickback down into the deployed position. Upon doing so, the horizontal member rises and collides with my chain, trying to press it into an 'S' bend.

      I've got a smaller chainring on the way, which may partially address the issue. But I see no other options other than to run with just enough slack in the chain that it can absorb this "hit."

      Has anyone run into this particular issue (interference when deployed, as opposed to stowed)? One idea would be to cut a notch in the stand, and reinforce it with extra material on the opposite side.

      I'll post pictures later.
    • speedub_nate
      ... the Freeradical , above the Kickback kickstand, and life looks good. ... deployed position. Upon doing so, the horizontal member rises and collides with my
      Message 2 of 23 , Feb 7, 2010
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        --- In rootsradicals@yahoogroups.com, "speedub_nate" <speedub.nate@...> wrote:

        > I've got the chain on my Xtracycle conversion threaded neatly under the Freeradical , above the Kickback kickstand, and life looks good.

        > Good, however, turns to ugly when I extend the Kickback down into the deployed position. Upon doing so, the horizontal member rises and collides with my chain, trying to press it into an 'S' bend.

        Pictures of my Problem:

        Ride (threading the needle): http://bit.ly/dbRI5D  
        Relax (** CruncH!! **): http://bit.ly/a2lWAu  

      • Jeff Snavely
        Yea, going over the bar is a bad idea. Big chainring, big freewheel and go under. The only reason I had issues running under is because I am limited in the
        Message 3 of 23 , Feb 7, 2010
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          Yea, going over the bar is a bad idea.  Big chainring, big freewheel and go under.

          The only reason I had issues running under is because I am limited in the chainring size I can run due to stokemonkey clearance.








          On Sun, Feb 7, 2010 at 7:00 PM, speedub_nate <speedub.nate@...> wrote:
           


          --- In rootsradicals@yahoogroups.com, "speedub_nate" <speedub.nate@...> wrote:

          > I've got the chain on my Xtracycle conversion threaded neatly under the Freeradical , above the Kickback kickstand, and life looks good.
          >
          > Good, however, turns to ugly when I extend the Kickback down into the deployed position. Upon doing so, the horizontal member rises and collides with my chain, trying to press it into an 'S' bend.


          Pictures of my Problem:

          Ride (threading the needle): http://bit.ly/dbRI5D
          Relax (** CruncH!! **): http://bit.ly/a2lWAu



        • speedub_nate
          ... and go ... It tastes too good; can t give it up! As shown in the pics I linked, 38x16. Final ratio needs to be around 2:1, so either 38T or 40T x 2o. I m
          Message 4 of 23 , Feb 8, 2010
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            --- In rootsradicals@yahoogroups.com, Jeff Snavely <jsnavely@...> wrote:
            >
            > Yea, going over the bar is a bad idea. Big chainring, big freewheel and go
            > under.

            It tastes too good; can't give it up!

            As shown in the pics I linked, 38x16. Final ratio needs to be around 2:1, so either 38T or 40T x 2o. I'm not going to find a reasonably-priced freewheel larger than 20T (Nuvinci uses thread-on BMX type freewheels, for anybody reading this who is unfamiliar with the hub). That pretty well limits me to a 40T chainring max -- so no way am I going to be able to get the chain to run under the Kickback (or over, with respect to the upside-down bike in the photos). In fact, to do so, I think I'd need to run a 60T chainring, which would necessitate a 30T freewheel .

            So I've got a 31T chainring in the mail to mate to this 16T freewheel. 31x16 is the right ratio, and will allow me to get the chain a little further from the Kickback. But it won't prevent the conflict in the "crunch" photo from happening.

            By hook or by crook, I'm going to find a way to run this without an idler or a tensioner. It would be a shame not to. 

            I've got a little bit of tire clearance to add reinforcement material to the back side of the Kickback, then gouge out a chunk to clear the chain. But I've got to evaluate how this will impact the integrity of the stand.

            BTW, I've got a roll of PVC tape and a rubber strip to protect the chain-on-frame contact that will inevitably occur as I'm bouncing down the street, so I'm not overly concerned about getting the chain too close to the underside of the front bridge.

            Still shopping for more suggestions.
          • Neil Walsh
            Why do you need a 2:1 ratio? I have 48 x 16 on my Nuvinci with Kickback and no problems. I would think having a 2:1 ratio on the Nuvinci would lead to a lot of
            Message 5 of 23 , Feb 8, 2010
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              Why do you need a 2:1 ratio? I have 48 x 16 on my Nuvinci with Kickback and no problems. I would think having a 2:1 ratio on the Nuvinci would lead to a lot of spinning out.

              Neil

              On Mon, Feb 8, 2010 at 8:26 AM, speedub_nate <speedub.nate@...> wrote:
               

              --- In rootsradicals@yahoogroups.com, Jeff Snavely <jsnavely@...> wrote:
              >
              > Yea, going over the bar is a bad idea. Big chainring, big freewheel and go
              > under.

              It tastes too good; can't give it up!

              As shown in the pics I linked, 38x16. Final ratio needs to be around 2:1, so either 38T or 40T x 2o. I'm not going to find a reasonably-priced freewheel larger than 20T (Nuvinci uses thread-on BMX type freewheels, for anybody reading this who is unfamiliar with the hub). That pretty well limits me to a 40T chainring max -- so no way am I going to be able to get the chain to run under the Kickback (or over, with respect to the upside-down bike in the photos). In fact, to do so, I think I'd need to run a 60T chainring, which would necessitate a 30T freewheel .

              So I've got a 31T chainring in the mail to mate to this 16T freewheel. 31x16 is the right ratio, and will allow me to get the chain a little further from the Kickback. But it won't prevent the conflict in the "crunch" photo from happening.

              By hook or by crook, I'm going to find a way to run this without an idler or a tensioner. It would be a shame not to. 

              I've got a little bit of tire clearance to add reinforcement material to the back side of the Kickback, then gouge out a chunk to clear the chain. But I've got to evaluate how this will impact the integrity of the stand.

              BTW, I've got a roll of PVC tape and a rubber strip to protect the chain-on-frame contact that will inevitably occur as I'm bouncing down the street, so I'm not overly concerned about getting the chain too close to the underside of the front bridge.

              Still shopping for more suggestions.

            • speedub_nate
              ... Kickback and ... lead to a ... Whaaat? That sounds really tall. You re OK climbing hills with that with a load? I have to get this bike home. I m just
              Message 6 of 23 , Feb 8, 2010
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                --- In rootsradicals@yahoogroups.com, Neil Walsh <walsh.neil@...> wrote:
                >
                > Why do you need a 2:1 ratio? I have 48 x 16 on my Nuvinci with Kickback and
                > no problems. I would think having a 2:1 ratio on the Nuvinci would lead to a
                > lot of spinning out.


                Whaaat? That sounds really tall. You're OK climbing hills with that with a load? I have to get this bike home. I'm just looking over their gearing chart and it looks like, at 2:1, about 27-28 inches in low gear. 

                Having been dragging around a loaded baby trailer with approximately the same low gear, I don't think I want to go any lower.
              • Jeff Snavely
                Didn t even notice you weren t using a tensioner. Yea... you can t go under the kickback without one. I think you re going to have chain retention problems,
                Message 7 of 23 , Feb 8, 2010
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                  Didn't even notice you weren't using a tensioner. Yea... you can't go under the kickback without one.

                  I think you're going to have chain retention problems, without one, but hopefully not.



                  On Mon, Feb 8, 2010 at 3:26 AM, speedub_nate <speedub.nate@...> wrote:
                   


                  --- In rootsradicals@yahoogroups.com, Jeff Snavely <jsnavely@...> wrote:
                  >
                  > Yea, going over the bar is a bad idea. Big chainring, big freewheel and go
                  > under.

                  It tastes too good; can't give it up!

                  As shown in the pics I linked, 38x16. Final ratio needs to be around 2:1, so either 38T or 40T x 2o. I'm not going to find a reasonably-priced freewheel larger than 20T (Nuvinci uses thread-on BMX type freewheels, for anybody reading this who is unfamiliar with the hub). That pretty well limits me to a 40T chainring max -- so no way am I going to be able to get the chain to run under the Kickback (or over, with respect to the upside-down bike in the photos). In fact, to do so, I think I'd need to run a 60T chainring, which would necessitate a 30T freewheel .

                  So I've got a 31T chainring in the mail to mate to this 16T freewheel. 31x16 is the right ratio, and will allow me to get the chain a little further from the Kickback. But it won't prevent the conflict in the "crunch" photo from happening.

                  By hook or by crook, I'm going to find a way to run this without an idler or a tensioner. It would be a shame not to. 

                  I've got a little bit of tire clearance to add reinforcement material to the back side of the Kickback, then gouge out a chunk to clear the chain. But I've got to evaluate how this will impact the integrity of the stand.

                  BTW, I've got a roll of PVC tape and a rubber strip to protect the chain-on-frame contact that will inevitably occur as I'm bouncing down the street, so I'm not overly concerned about getting the chain too close to the underside of the front bridge.

                  Still shopping for more suggestions.

                • speedub_nate
                  ... under ... but ... Oooh, that would suck if I go through all this trouble just to find I can t keep a chain. I d better ride this a while without the
                  Message 8 of 23 , Feb 8, 2010
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                    --- In rootsradicals@yahoogroups.com, Jeff Snavely <jsnavely@...> wrote:
                    >
                    > Didn't even notice you weren't using a tensioner. Yea... you can't go under
                    > the kickback without one.
                    >
                    > I think you're going to have chain retention problems, without one, but
                    > hopefully not.

                    Oooh, that would suck if I go through all this trouble just to find I can't keep a chain. I'd better ride this a while without the Kickback installed to see if that ends up being a problem.

                    So I ran some numbers and found that if I run a 60T ring in the front, it'll lower the chain by 1-3/4", and if I run a 30T cog in the rear, it'll lower the chain by 1-1/4", so I could expect a change of 1-1/2" right by the point of conflict. Add in some play at the EBB (it's rotated into a "high crank" position as pictured). 

                    So in all likelyhood, I could go blow $75 on an oversized 30T freewheel, throw a 60T chainring on, and I'll be in business without having to get the grinder out.

                    Decisions, decisions...

                  • ama3655@aol.com
                    I don t remember if your bike had horizontal or vertical dropouts, but if vertical you will need a chain tensioner. The chain could conceivably fit well right
                    Message 9 of 23 , Feb 8, 2010
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                      I don't remember if your bike had horizontal or vertical dropouts, but if vertical you will need a chain tensioner. The chain could conceivably fit well right now, or be made to with a half link. But over time things wear and the chain will loosen up a bit. With no adjustment available things will probably not work out well.
                       
                      FatRob
                       
                      In a message dated 2/8/2010 9:07:39 A.M. Central Standard Time, speedub.nate@... writes:
                      Oooh, that would suck if I go through all this trouble just to find I can't keep a chain. I'd better ride this a while without the Kickback installed to see if that ends up being a problem.

                      So I ran some numbers and found that if I run a 60T ring in the front, it'll lower the chain by 1-3/4", and if I run a 30T cog in the rear, it'll lower the chain by 1-1/4", so I could expect a change of 1-1/2" right by the point of conflict. Add in some play at the EBB (it's rotated into a "high crank" position as pictured).  

                      So in all likelyhood, I could go blow $75 on an oversized 30T freewheel, throw a 60T chainring on, and I'll be in business without having to get the grinder out.

                      Decisions, decisions...
                       
                    • todd
                      get a terracycle idler kit: http://www.flickr.com/photos/cleverchimp/4222517995/
                      Message 10 of 23 , Feb 8, 2010
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                        get a terracycle idler kit: http://www.flickr.com/photos/cleverchimp/4222517995/

                        --- In rootsradicals@yahoogroups.com, "speedub_nate" <speedub.nate@...> wrote:
                        >
                        > --- In rootsradicals@yahoogroups.com, Jeff Snavely <jsnavely@> wrote:
                        > >
                        > > Didn't even notice you weren't using a tensioner. Yea... you can't go
                        > under
                        > > the kickback without one.
                        > >
                        > > I think you're going to have chain retention problems, without one,
                        > but
                        > > hopefully not.
                        > Oooh, that would suck if I go through all this trouble just to find I
                        > can't keep a chain. I'd better ride this a while without the Kickback
                        > installed to see if that ends up being a problem.
                        > So I ran some numbers and found that if I run a 60T ring in the front,
                        > it'll lower the chain by 1-3/4", and if I run a 30T cog in the rear,
                        > it'll lower the chain by 1-1/4", so I could expect a change of 1-1/2"
                        > right by the point of conflict. Add in some play at the EBB (it's
                        > rotated into a "high crank" position as pictured).
                        > So in all likelyhood, I could go blow $75 on an oversized 30T freewheel,
                        > throw a 60T chainring on, and I'll be in business without having to get
                        > the grinder out.
                        > Decisions, decisions...
                        >
                      • Galen Fitzpatrick
                        does he need a chain tensioner since he has the eccentric bottom bracket? -Galen
                        Message 11 of 23 , Feb 8, 2010
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                          does he need a chain tensioner since he has the eccentric bottom bracket?

                          -Galen

                          On Mon, Feb 8, 2010 at 11:59 AM, todd <todd@...> wrote:
                           

                          get a terracycle idler kit: http://www.flickr.com/photos/cleverchimp/4222517995/



                          --- In rootsradicals@yahoogroups.com, "speedub_nate" <speedub.nate@...> wrote:
                          >
                          > --- In rootsradicals@yahoogroups.com, Jeff Snavely <jsnavely@> wrote:
                          > >
                          > > Didn't even notice you weren't using a tensioner. Yea... you can't go
                          > under
                          > > the kickback without one.
                          > >
                          > > I think you're going to have chain retention problems, without one,
                          > but
                          > > hopefully not.
                          > Oooh, that would suck if I go through all this trouble just to find I
                          > can't keep a chain. I'd better ride this a while without the Kickback
                          > installed to see if that ends up being a problem.
                          > So I ran some numbers and found that if I run a 60T ring in the front,
                          > it'll lower the chain by 1-3/4", and if I run a 30T cog in the rear,
                          > it'll lower the chain by 1-1/4", so I could expect a change of 1-1/2"
                          > right by the point of conflict. Add in some play at the EBB (it's
                          > rotated into a "high crank" position as pictured).
                          > So in all likelyhood, I could go blow $75 on an oversized 30T freewheel,
                          > throw a 60T chainring on, and I'll be in business without having to get
                          > the grinder out.
                          > Decisions, decisions...
                          >


                        • Neil Walsh
                          This looks interesting - which model best suits the BD? Neil
                          Message 12 of 23 , Feb 8, 2010
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                            This looks interesting - which model best suits the BD?

                            Neil

                            On Mon, Feb 8, 2010 at 4:59 PM, todd <todd@...> wrote:
                             

                            get a terracycle idler kit: http://www.flickr.com/photos/cleverchimp/4222517995/



                            --- In rootsradicals@yahoogroups.com, "speedub_nate" <speedub.nate@...> wrote:
                            >
                            > --- In rootsradicals@yahoogroups.com, Jeff Snavely <jsnavely@> wrote:
                            > >
                            > > Didn't even notice you weren't using a tensioner. Yea... you can't go
                            > under
                            > > the kickback without one.
                            > >
                            > > I think you're going to have chain retention problems, without one,
                            > but
                            > > hopefully not.
                            > Oooh, that would suck if I go through all this trouble just to find I
                            > can't keep a chain. I'd better ride this a while without the Kickback
                            > installed to see if that ends up being a problem.
                            > So I ran some numbers and found that if I run a 60T ring in the front,
                            > it'll lower the chain by 1-3/4", and if I run a 30T cog in the rear,
                            > it'll lower the chain by 1-1/4", so I could expect a change of 1-1/2"
                            > right by the point of conflict. Add in some play at the EBB (it's
                            > rotated into a "high crank" position as pictured).
                            > So in all likelyhood, I could go blow $75 on an oversized 30T freewheel,
                            > throw a 60T chainring on, and I'll be in business without having to get
                            > the grinder out.
                            > Decisions, decisions...
                            >


                          • speedub_nate
                            ... No. The EBB is the impetus behind doing this tensionerless. So, two options: hack the Kickback (either literally or figuratively), or run with the
                            Message 13 of 23 , Feb 8, 2010
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                              --- In rootsradicals@yahoogroups.com, Galen Fitzpatrick <galen.fitzpatrick@...> wrote:
                              >
                              > does he need a chain tensioner since he has the eccentric bottom bracket?


                              No. The EBB is the impetus behind doing this tensionerless.

                              So, two options: hack the Kickback (either literally or figuratively), or run with the oversized freewheel.

                              The kickstand hack would me more trouble for me up front, but more easily sustainable in the long run.

                              In my opinion, it would be criminal to run a tensioner or idler on this frame.
                            • Rick Pickett
                              yeah, don t ruin the beautiful tensioner-less chain line (I m constantly bummed that I can t on my Rolhoff, but then I recall I have a Rolhoff and life is
                              Message 14 of 23 , Feb 8, 2010
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                                yeah, don't ruin the beautiful tensioner-less chain line (I'm constantly bummed that I can't on my Rolhoff, but then I recall I have a Rolhoff and life is grand again...)... That being said, even with my tensioner, I have a slight amount of chain rub when in the "ride/up" position, just enough to buff the powedercoat off.

                                wish I could help out with a solution...

                                "Melancholy is incompatible with bicycling."  – James E. Starrs

                                artistic shenaniganizer | rick@...
                                888.537-1401 x709 | every day adventure





                                On Feb 8, 2010, at 9:55 AM, speedub_nate wrote:

                                 



                                --- In rootsradicals@ yahoogroups. com, Galen Fitzpatrick <galen.fitzpatrick@ ...> wrote:
                                >
                                > does he need a chain tensioner since he has the eccentric bottom bracket?

                                No. The EBB is the impetus behind doing this tensionerless.

                                So, two options: hack the Kickback (either literally or figuratively) , or run with the oversized freewheel.

                                The kickstand hack would me more trouble for me up front, but more easily sustainable in the long run.

                                In my opinion, it would be criminal to run a tensioner or idler on this frame.


                              • Steve Lange
                                ... With all due respect, this is a cargo bike. I d run what made it easiest to accomplish the main function of the bike in the most reliable / serviceable
                                Message 15 of 23 , Feb 8, 2010
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                                  On Mon, Feb 8, 2010 at 9:55 AM, speedub_nate <speedub.nate@...> wrote:

                                  > In my opinion, it would be criminal to run a tensioner or idler on this frame.

                                  With all due respect, this is a cargo bike. I'd run what made it
                                  easiest to accomplish the main function of the bike in the most
                                  reliable / serviceable manner possible. Sounds like a chain tensioner
                                  solves 100% of the chain interference issue and doesn't require any
                                  funky sized components.

                                  Just sayin'

                                  Steve Lange
                                  Santa Barbara, CA
                                • todd
                                  i think you ll find that the lower chain run will slap on the bottom of the front bridge without any tensioner or idler. even a very stiff frame will flex
                                  Message 16 of 23 , Feb 8, 2010
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                                    i think you'll find that the lower chain run will slap on the bottom of the front bridge without any tensioner or idler. even a very stiff frame will flex enough over this long a run that a statically tensioned chain will either be too tight or too loose transiently -- not good on many fronts.

                                    btw an idler directing the chain over the front bridge means that a belt drive is a possibility...

                                    about which terracycle kit - it's sort of a kit of parts rather than a package. suggest calling and describing what you want, using our video clip as a reference if that's it.

                                    i'm going to be off the grid for a couple days so any follow-up will be delayed.


                                    --- In rootsradicals@yahoogroups.com, Rick Pickett <rick@...> wrote:
                                    >
                                    > yeah, don't ruin the beautiful tensioner-less chain line (I'm constantly bummed that I can't on my Rolhoff, but then I recall I have a Rolhoff and life is grand again...)... That being said, even with my tensioner, I have a slight amount of chain rub when in the "ride/up" position, just enough to buff the powedercoat off.
                                    >
                                    > wish I could help out with a solution...
                                    >
                                    > "Melancholy is incompatible with bicycling." � James E. Starrs
                                    >
                                    > artistic shenaniganizer | rick@...
                                    > 888.537-1401 x709 | every day adventure
                                    >
                                    >
                                    >
                                    >
                                    >
                                    > On Feb 8, 2010, at 9:55 AM, speedub_nate wrote:
                                    >
                                    > >
                                    > >
                                    > > --- In rootsradicals@yahoogroups.com, Galen Fitzpatrick <galen.fitzpatrick@> wrote:
                                    > > >
                                    > > > does he need a chain tensioner since he has the eccentric bottom bracket?
                                    > >
                                    > > No. The EBB is the impetus behind doing this tensionerless.
                                    > >
                                    > > So, two options: hack the Kickback (either literally or figuratively), or run with the oversized freewheel.
                                    > >
                                    > > The kickstand hack would me more trouble for me up front, but more easily sustainable in the long run.
                                    > >
                                    > > In my opinion, it would be criminal to run a tensioner or idler on this frame.
                                    > >
                                    > >
                                    >
                                  • speedub_nate
                                    ... No offense taken, Steve, and none intended when I say that I could have much more easily (and cheaply) purchased a Big Dummy, or repurposed any old beat up
                                    Message 17 of 23 , Feb 8, 2010
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                                      --- In rootsradicals@yahoogroups.com, Steve Lange <steve@...> wrote:
                                      > With all due respect, this is a cargo bike...

                                      No offense taken, Steve, and none intended when I say that I could have much more easily (and cheaply) purchased a Big Dummy, or repurposed any old beat up 26" hardtail.

                                      A bike can be many things, and there is an undeniable aesthetic that comes with a simple singlespeed chainline that holds enough charm that this is worth pursuing. Obviously, not everybody agrees, and I have no problem with that.

                                      The stars aligned when this frame fell into my hands. I've can't ignore the urge to run with it and make the EBB work for me.
                                    • Rich
                                      Rob; In an earlier post it was mentioned I believe that the OP s frame has an eccentric bottom bracket for chain tensioning. I have a similar design frame
                                      Message 18 of 23 , Feb 8, 2010
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                                        Rob;

                                        In an earlier post it was mentioned I believe that the OP's frame has an eccentric bottom bracket for chain tensioning. I have a similar design frame with an IGH, the Steelwool Tweed. No Xtracycle or Kickback on it however as it is set up as a sporty IGH bike with drop bars and an Alfine hub with Jtek shifter.

                                        The 2:1 ratio the OP spoke of will give about a 26" to 91" gearing with the NuVinci hub. If using it in a area with hills on a cargo bike I would not personally want to go much higher on the gearing and the high is higher than the stock gearing on the Yuba Mundo. An opportunity to learn to spin and still higher than the gearing on most cruisers or current 3 speed IGH bikes such as the Electras IIRC. My Trek 950 with NuVinci hub and 2" Big Apple tires is set up with a 2 to 1 ratio using 17/34 gearing. Due to vertical dropouts on the frame I have to run my NuVinci with the Nuvinci chain tensioner.

                                        The 3:1 input gearing (16:48) mentioned by another poster for the NuVinci seems a bit high as the low is about 39" and the high is 136" with 26" tires. This seems overly high for a cargo bike, at least to me. Personally though I want a relatively low lowest gear on my bikes.

                                        Unfortunately no ready solution to the OPs center stand problem other than possibly seeing if the Jackass centerstand will work without interference with his chain line. Another possibility, aesthetically undesirable, is the possible use of the Rohloff dual idler tensioner. Based on pictures it looks like it would likely clear the NuVinci hub's shift box and it is intended for the same chain line as the NuVinci hub has, about 54mm IIRC.

                                        The very large chainring and rear freewheel sprocket the OP has spoken of would look a bit wierd to me. BTW per one post on BF the NuVinci can be run w/o a freewheel as the internal drive design cannot transmit torque in the reverse direction. The poster indicated that there is alight torque felt on the pedals when coasting and they tend to rotate forward when pushing the bike. Otherwise no problems with this setup. I have not tried it however.

                                        Rich Wood


                                        --- In rootsradicals@yahoogroups.com, ama3655@... wrote:
                                        >
                                        >
                                        > I don't remember if your bike had horizontal or vertical dropouts, but if
                                        > vertical you will need a chain tensioner. The chain could conceivably fit
                                        > well right now, or be made to with a half link. But over time things wear and
                                        > the chain will loosen up a bit. With no adjustment available things will
                                        > probably not work out well.
                                        >
                                        > FatRob
                                        >
                                        > In a message dated 2/8/2010 9:07:39 A.M. Central Standard Time,
                                        > speedub.nate@... writes:
                                        >
                                        > Oooh, that would suck if I go through all this trouble just to find I
                                        > can't keep a chain. I'd better ride this a while without the Kickback installed
                                        > to see if that ends up being a problem.
                                        >
                                        >
                                        > So I ran some numbers and found that if I run a 60T ring in the front,
                                        > it'll lower the chain by 1-3/4", and if I run a 30T cog in the rear, it'll
                                        > lower the chain by 1-1/4", so I could expect a change of 1-1/2" right by the
                                        > point of conflict. Add in some play at the EBB (it's rotated into a "high
                                        > crank" position as pictured).
                                        >
                                        >
                                        > So in all likelyhood, I could go blow $75 on an oversized 30T freewheel,
                                        > throw a 60T chainring on, and I'll be in business without having to get the
                                        > grinder out.
                                        >
                                        >
                                        > Decisions, decisions...
                                        >
                                      • Rich
                                        BTW with an eccentric bottom bracket is there any chance that the eccentric assembly can be rotated 180 degrees so that the chain run from the front chainring
                                        Message 19 of 23 , Feb 9, 2010
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                                          BTW with an eccentric bottom bracket is there any chance that the eccentric assembly can be rotated 180 degrees so that the chain run from the front chainring is moved enough to minimize or eliminate the interference with the Kickback? There ought to be two positions of the EBB where the chain tension is correct.

                                          Rich Wood


                                          --- In rootsradicals@yahoogroups.com, "Rich" <astronut1001@...> wrote:
                                          >
                                          > Rob;
                                          >
                                          > In an earlier post it was mentioned I believe that the OP's frame has an eccentric bottom bracket for chain tensioning. I have a similar design frame with an IGH, the Steelwool Tweed. No Xtracycle or Kickback on it however as it is set up as a sporty IGH bike with drop bars and an Alfine hub with Jtek shifter.
                                          >
                                          > The 2:1 ratio the OP spoke of will give about a 26" to 91" gearing with the NuVinci hub. If using it in a area with hills on a cargo bike I would not personally want to go much higher on the gearing and the high is higher than the stock gearing on the Yuba Mundo. An opportunity to learn to spin and still higher than the gearing on most cruisers or current 3 speed IGH bikes such as the Electras IIRC. My Trek 950 with NuVinci hub and 2" Big Apple tires is set up with a 2 to 1 ratio using 17/34 gearing. Due to vertical dropouts on the frame I have to run my NuVinci with the Nuvinci chain tensioner.
                                          >
                                          > The 3:1 input gearing (16:48) mentioned by another poster for the NuVinci seems a bit high as the low is about 39" and the high is 136" with 26" tires. This seems overly high for a cargo bike, at least to me. Personally though I want a relatively low lowest gear on my bikes.
                                          >
                                          > Unfortunately no ready solution to the OPs center stand problem other than possibly seeing if the Jackass centerstand will work without interference with his chain line. Another possibility, aesthetically undesirable, is the possible use of the Rohloff dual idler tensioner. Based on pictures it looks like it would likely clear the NuVinci hub's shift box and it is intended for the same chain line as the NuVinci hub has, about 54mm IIRC.
                                          >
                                          > The very large chainring and rear freewheel sprocket the OP has spoken of would look a bit wierd to me. BTW per one post on BF the NuVinci can be run w/o a freewheel as the internal drive design cannot transmit torque in the reverse direction. The poster indicated that there is alight torque felt on the pedals when coasting and they tend to rotate forward when pushing the bike. Otherwise no problems with this setup. I have not tried it however.
                                          >
                                          > Rich Wood
                                          >
                                          >
                                          > --- In rootsradicals@yahoogroups.com, ama3655@ wrote:
                                          > >
                                          > >
                                          > > I don't remember if your bike had horizontal or vertical dropouts, but if
                                          > > vertical you will need a chain tensioner. The chain could conceivably fit
                                          > > well right now, or be made to with a half link. But over time things wear and
                                          > > the chain will loosen up a bit. With no adjustment available things will
                                          > > probably not work out well.
                                          > >
                                          > > FatRob
                                          > >
                                          > > In a message dated 2/8/2010 9:07:39 A.M. Central Standard Time,
                                          > > speedub.nate@ writes:
                                          > >
                                          > > Oooh, that would suck if I go through all this trouble just to find I
                                          > > can't keep a chain. I'd better ride this a while without the Kickback installed
                                          > > to see if that ends up being a problem.
                                          > >
                                          > >
                                          > > So I ran some numbers and found that if I run a 60T ring in the front,
                                          > > it'll lower the chain by 1-3/4", and if I run a 30T cog in the rear, it'll
                                          > > lower the chain by 1-1/4", so I could expect a change of 1-1/2" right by the
                                          > > point of conflict. Add in some play at the EBB (it's rotated into a "high
                                          > > crank" position as pictured).
                                          > >
                                          > >
                                          > > So in all likelyhood, I could go blow $75 on an oversized 30T freewheel,
                                          > > throw a 60T chainring on, and I'll be in business without having to get the
                                          > > grinder out.
                                          > >
                                          > >
                                          > > Decisions, decisions...
                                          > >
                                          >
                                        • speedub_nate
                                          ... eccentric assembly can be rotated 180 degrees so that the chain run from the front chainring is moved enough to minimize or eliminate the interference with
                                          Message 20 of 23 , Feb 9, 2010
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                                            --- In rootsradicals@yahoogroups.com, "Rich" <astronut1001@...> wrote:
                                            >
                                            > BTW with an eccentric bottom bracket is there any chance that the eccentric assembly can be rotated 180 degrees so that the chain run from the front chainring is moved enough to minimize or eliminate the interference with the Kickback?

                                             

                                            Yes, the EBB can hold the bottom bracket in either a "high" and a "low" position. Neither one offers the chain a straight shot in past the Kickback (basically, the "lowest" straight line the chain can run is limited by the forward bridge; the deployed Kickback impinges on this imaginary line.

                                            I'm going to take this to a local frame builder and ask if he can crimp the offending Kickback tube, then re-weld it to the plate that joins the two halves. I think that ought to do the trick.

                                          • Pete B
                                            Nate, It from the photo s it would appear you have quite a bit of chain clearance over the top of the front Horizontal Tube of the FreeRad but inadequate
                                            Message 21 of 23 , Feb 14, 2010
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                                            Nate,

                                            It from the photo's it would appear you have quite a bit of chain clearance over the top of the front Horizontal Tube of the FreeRad but inadequate clearance underneath. 

                                            Also looking at the photo of the bike in mock-up http://www.booboodog.net/images/bikes/xtra/xtra-os-1.jpg it would appear that the front tongue of the FreeRad may be sitting a little too low (see the attached pic). Possibly due to the unique geometry of the donor frame.

                                            Taking a look at the dimensions Surly settled on for the BD  http://surlybikes.com/frames/big_dummy_frame/ they appear to have designed it to have the front dropouts, rear dropouts and (theoretical) FreeRad Mount points in a flat plane. Whereas it appears your's drop by around 1 inch where the FreeRad attaches to the donor frame dropouts.

                                            Also they spec their Bottom Bracket centre at 1.6 inches below the plane from front to rear dropouts. Your setup appears to be around 4 inches.
                                              
                                            You could try changing the geometry by raising the height of the Front attachment point of the FreeRad, You could do this by stacking washers between the tongue and the chainstay bridge plate or by sitting it on top of a FAP resting on top of the chainstays.

                                            Every bit you raise the front tongue will trade chain clearance above the bar for extra chain clearance under the Kickback stand.

                                            Just my 2 cents.

                                            Rgds
                                            Pete.B
                                             

                                            'Newspapers are unable, seemingly, to discriminate between a bicycle accident and the collapse of civilization' : George Bernard Shaw



                                            On 10 February 2010 09:06, speedub_nate <speedub.nate@...> wrote:
                                             

                                            --- In rootsradicals@yahoogroups.com, "Rich" <astronut1001@...> wrote:
                                            >
                                            > BTW with an eccentric bottom bracket is there any chance that the eccentric assembly can be rotated 180 degrees so that the chain run from the front chainring is moved enough to minimize or eliminate the interference with the Kickback?

                                             

                                            Yes, the EBB can hold the bottom bracket in either a "high" and a "low" position. Neither one offers the chain a straight shot in past the Kickback (basically, the "lowest" straight line the chain can run is limited by the forward bridge; the deployed Kickback impinges on this imaginary line.

                                            I'm going to take this to a local frame builder and ask if he can crimp the offending Kickback tube, then re-weld it to the plate that joins the two halves. I think that ought to do the trick.


                                          • speedub_nate
                                            ... sitting a little too low. Possibly due to the unique geometry of the donor frame. ... appear to have designed it to have the front dropouts, rear
                                            Message 22 of 23 , Feb 15, 2010
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                                              --- In rootsradicals@yahoogroups.com, Pete B <nackterman@...> wrote:
                                              >
                                              > ...it would appear that the front tongue of the FreeRad may 
                                              > be sitting a little too low. Possibly due to the unique 
                                              > geometry of the donor frame.
                                              >
                                              > Taking a look at the dimensions Surly settled on for the BD 
                                              > they appear to have designed it to have the front dropouts, 
                                              > rear dropouts and (theoretical) FreeRad Mount points in a 
                                              > flat plane. Whereas it appears your's drop by around 1 inch 
                                              > where the FreeRad attaches to the donor frame dropouts.
                                              >
                                              > Also they spec their Bottom Bracket centre at 1.6 inches 
                                              > below the plane from front to rear dropouts. Your setup 
                                              > appears to be around 4 inches.
                                              >
                                              > You could try changing the geometry by raising the height of 
                                              > the Front attachment point of the FreeRad...

                                              Pete, good points, but I've got to give consideration to two things:

                                               - My head tube angle is right where I want it. Jacking the FR tongue higher would steepen this angle. This is something I can play with once I hit the road, but I'm smack in the 73.5°-74° range, and don't have more than .5° to 1° to play with. I estimate the head angle will steepen .5° for every 20mm I raise the FR tongue off the chainstay bridge, which isn't much, but it would take a lot of lift to get the chain to clear under the FR's front bridge.

                                               - The front wheel is 29"/700c, so compared to a 26" bike, the bottom bracket drop relative to the front axle is supposed to be lower (so as not to increase my center of gravity). The line you drew would be horizontal on a Big Dummy, but on this bike it slopes upward from the rear axle to the front axle. I realize the BB is slightly lower than ideal, but raising it would steepen the head tube angle.

                                              A 31T chainring arrived in Saturday's mail. I'll take some time Monday morning to get this thing on the road without the Kickback, and we'll see where that leads me. If it all works out OK, I'll plan a visit to my framebuilder to devise a way to crimp, grind and/or weld my way out of the kickstand/chain clearance problem.

                                              More to come...
                                            • speedub_nate
                                              ... I don t want to derail this topic, so I posted my first ride / first impressions and new photos on MTBR s cargo bike forum: http://bit.ly/cQbOh6
                                              Message 23 of 23 , Feb 18, 2010
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                                                --- In rootsradicals@yahoogroups.com, "speedub_nate" <speedub.nate@...> wrote:

                                                > I'll take some time Monday
                                                > morning to get this thing on the road without the Kickback, and we'll
                                                > see where that leads me.
                                                >
                                                > More to come...

                                                I don't want to derail this topic, so I posted my first ride / first impressions and new photos on MTBR's cargo bike forum: http://bit.ly/cQbOh6

                                                I'll post back here when I make progress with the kickstand issue.

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